696
FXUS21 KWNC 011814
PMDTHR
US Hazards Outlook
NWS Climate Prediction Center College Park MD
300 PM EDT July 01 2025

SYNOPSIS: Mid-level high pressure is forecast to strengthen and slowly
retrograde into the western contiguous U.S. (CONUS) during week-2. This
supports an increased risk of extreme heat across portions of the Northwest,
extending southward through the California Central Valley and Desert Southwest.
Extreme heat also remains a concern across the Southern Plains and Lower
Mississippi Valley due to elevated humidity levels combined with above-normal
temperatures. Monsoon activity remains forecast across the Southwest, further
enhanced by continued tropical cyclone activity across the East Pacific. A slow
moving frontal system favors increased chances of heavy precipitation across
portions of the southeastern U.S. and Mid-Atlantic.

HAZARDS

Slight risk of extreme heat across portions of the Southern Plains and Lower
Mississippi Valley, Wed-Sat, Jul 9-12.

Slight risk of extreme heat across portions of the Southwest, Interior
California, the Pacific Northwest, Great Basin, and Northern Rockies, Wed-Tue,
Jul 9-15.

Slight risk of heavy precipitation across portions of the Southwest, Central
and Southern Rockies, and Central Great Basin, Wed-Tue, Jul 9-15.

Slight risk of heavy precipitation across portions of the Lower Mississippi and
Tennessee Valleys, Southern Appalachians, Mid-Atlantic, and Southeast, Wed-Sat,
Jul 9-12.

Flooding possible across portions of Arizona and New Mexico.

DETAILED SUMMARY

FOR FRIDAY JULY 04 - TUESDAY JULY 08:
https://www.wpc.ncep.noaa.gov/threats/threats.php

FOR WEDNESDAY JULY 09 - TUESDAY JULY 15: Mid-level ridging is predicted to
amplify while slowly retrograding into the western CONUS during week-2. The 0z
ECENS continues to depict a 597-dm ridge axis across the Four Corners early in
the period, with +60 meter positive height anomalies extending over much of the
Northwest. The 0z GEFS and CMCE are slightly less amplified compared to the
ECENS but depict the same general evolution. At the surface, this translates to
increasing chances for above-normal temperatures over much of the West. The
initial focus for elevated extreme heat potential is favored across the
Northwest, and then expanding southward through the California Central Valley
and Southwest based on the progression of 20 percent or greater probabilities
for temperatures exceeding the 85th climatological percentile in the GEFS and
ECENS Probabilistic Extremes Tools (PETs). A slight risk of extreme heat is
posted across portions of the Desert Southwest, Interior California, the
Pacific Northwest, Great Basin, and Northern Rockies for all of week-2.
Predicted temperatures based on the uncalibrated ECENS and GEFS range from the
mid-90s deg F across the northern Great Basin to possibly above 105 (110) deg F
across the California Central Valley (Desert Southwest).



Above-normal temperatures also remain forecast across portions of the Southern
Plains and Lower Mississippi Valley with forecast highs generally in the upper
90s to possibly the low 100s deg F across central Texas. Elevated humidity is
likely to boost heat index values by several degrees further increasing the
risk for extreme heat. However, heat signals are notably reduced compared to
yesterday as positive mid-level height anomalies shift more to the west and
troughing favors relatively cooler temperatures over portions of the Plains,
although the southward progression is more uncertain. The calibrated skill
weighted heat tool still depicts probabilities of 20-30 percent for heat index
values exceeding the 95th climatological percentile across portions of Texas
and northern Louisiana, with some areas potentially having heat index values of
105-110 deg F. As a result of these enhanced signals, the slight risk for
extreme heat continues through Jul 12 across portions of the Southern Plains
and Lower Mississippi Valley.



An active monsoon pattern remains forecast across the Southwest due to
favorable ridge axis placement across the Four Corners, combined with continued
tropical cyclone activity across the East Pacific. Although the ECENS PET has
backed off significantly with the precipitation signal compared to yesterday,
both the GEFS and ECENS PETs continue to show some areas of Arizona with at
least a 20 percent chance 3-day precipitation totals exceed a half-inch. The
uncalibrated guidance also favors daytime convection extending further east
into portions of Colorado and New Mexico. While the signals are arguably more
marginal, the slight risk of heavy precipitation continues for all of week-2 in
todays outlook. Any additional precipitation during week-2 is likely to worsen
saturated ground conditions and possibly trigger additional flooding in the
region. A flooding possible hazard remains issued where locally heavy
precipitation may also trigger flash flooding and debris flows near recently
burned areas. In addition to flash flooding, thunderstorm impacts may include
lightning, gusty winds and blowing dust. However, in spite of these potentially
adverse but localized impacts, some areas experiencing moderate to exceptional
drought conditions and wildfires will benefit from the enhanced rainfall.



Across the Ohio Valley and Mid-Atlantic, seasonably warm temperatures are
forecast beginning later in week-1 into the outset of week-2. Temperatures are
forecast to moderate by the middle of the period as troughing builds across the
East, with the 0z ECENS and CMCE depicting negative mid-level height anomalies
developing across the Ohio Valley and Great Lakes during the second half of the
period. A slow moving or stalled frontal system along the leading edge of the
trough favors elevated chances of heavy precipitation across portions of the
Eastern Seaboard and the Gulf Coast. Both the GEFS and ECENS PETs depict some
areas having at least a 20 percent chance 3-day precipitation totals exceed the
85th climatological percentile and 1-inch during the first half of the period.
Therefore, a slight risk of heavy precipitation is posted across portions of
the Lower Mississippi and Tennessee Valleys, Southern Appalachians,
Mid-Atlantic, and Southeast, Jul 9-12.



Shortwave troughing forecast to move across the Gulf of Alaska favors a
breakdown of ridging predicted during week-1. Following very warm temperatures
across northern Alaska in week-1, temperatures are likely to moderate going
into week-2. While above-normal precipitation is favored across much of
southern and eastern Alaska, precipitation amounts are not forecast to reach
hazards thresholds.

FORECASTER: Thomas Collow

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